Study On The Terms Of Seed Germination And Tissue Culture Of Dioscorea Zingiberensis, And Effects Of Temperature On Physiological Property Such As POD Activity In The Leaves Of Dioscorea Zingiberensis

In the first part of the paper, we study the terms of germination of Dioscorea zingiberensis seeds. It shows that the key factor for seed germination and high germination rate is to keep the balance between temperature and hormone inside and outside seed. In this experiment, 25 ℃ is the best temperature for it to bourgeon, and we can get a higher germination rate and the initialized number of days about 15 on the same medium under this temperature. The highest germination rate of Dioscorea zingiberensis seeds pretreated by asepsis water reaches 35.6 %on the medium of MS+ GA₃ 6.0 mg/L, and 30.0 %on the medium of MS+ GA₃ 2 mg/L if pretreated by GA₃ at 50mg/LIn the second part, the material is the asepsis young plant from seed germination, and disparate explants from the nodal segments, leaves and leafstalks are inoculated on twelve different kinds of culture medium made up of MS and different hormones, so that the most fitting induction medium can be selected. During the process, when there is only 6-BA or KT in the medium, all the explants became serious brown and no callus appears. The highest abduction rates of the callus from the nodal segments and leaves are 100% and 40% when the medium with single auxin: 2,4-D 4 mg/ L. The highest rate of the callus from Leafstalks is 28.6% on the medium of MS+6-BA 4.0 mg/L+NAA 1.0 mg/L.In the third part, the objective of the experiment is to selected differentiation culture medium and the medium of root formation, so that the fit term for plants regeneration is decided. On the differentiation culture medium, the calluses from leaves and leafstalks are becoming brown and then dead. The circumstance of the bud differentiation of callus from the nodal segments is different on different mediums. When only one cytokinin is in the medium, the differentiation rate is 5.4% in the medium with 6-BA, while no bud grows in the medium with KT. When there are both auxin and cytokinin, the combination of 6-Bt and NAA is evidently better than that of KT and NAA. On the medium of MS+6-BAlmg/L+NAA 0.5 mg/L, the differentiation rate is 68.4%, and 33.3% on the medium of MS +'NAA 0.5 mg/L + IAA 0.5 mg/L + 6-BA 0.5mg/L. Root formation from the shoot of Dioscorea zingiberensis is very difficult. There are few young plants can grown on the medium only with NAA/IAA. When NAA> IAA and 6 — BA are used on the same time, the medium is propitious to root formation of the shoot. The highest rate of root formation is 33.3% on the medium of 1/2 MS+6-BA0.5mg/L+NAA0.5mg/L+IAA 0.5rng/L.The trend relation between the growth temperature and the leaves of Dioscorea zingiberensis is studied in the forth part. Under 25 °C, the activities of POD, SOD and CAT, and the contents of MDA, soluble protein and soluble sugar change very little during ten days in the leaves of Dioscorea zingiberensis. When the plants of Dioscorea zingiberensis are cultured for five days respectively under 15 °C, 20 °C^ 30 °C and 35 °C, the activities of POD, SOD and CAT are higher than that of one day, and then decline when for ten days; Though CAT activity becomes lower than that of one day this time, and the activity of POD and SOD are still higher. Under 35 °C, the activities of POD and CAT show great changing ranges both of rising and decline, and under 15 °C, the changing range takes second place. The contents of MDA are higher than that of one day when the plants' are cultured for five days ,as well as ten days, and under 15 °C and 35 °C, the contents of MDA add most with . time gone by. The changing trend is corresponding as it shows M shape in the content of soluble protein and W shape in the content of soluble sugar. The contentsof soluble protein are rising, while the contents of soluble sugar are declining compared with that of one day under 20 °C and 30 °C; and the change takes the other way round under 15 °C and 35 "C.